Induction-motor control.



PATENTE? FEB. 6, 1906.

A. H. ARS'GNG. INDUCTION MR CONTROL.

2 SHEETS-BREST 1.

APILIGAIDE FILED .TUNE 2S, 1905.

inventor: wmston annif.

No. 811,758. PATENTBD FEB. 6, 1906. A. H. ARMSTRONG.

INDUCTION MTOR GNTRUL.

APPLIOATIN FILED SSFS 3B, 19"(35.

2 SHEBTB-SEBT 2.

muy

UN ITEI) STATES PATENT OFFICE.

ALBERT Il. ARMFRONG, OF SCHNECTADY, NEW YORK, ASSIGNOR TO (.ENlCltA L IQLFXFRIC' COMPNY, A CORPORATION OF NEW YORK.

INDUCTION-MOTOR CONTROL.

Speccation of Letters Patent.

Patented Feb. 6, 1906.

Application filed June 28, 1905. Serial No 2872341.

To mit whom t may concern,.-

Bo tknown that LALnanril. Ansisrnono, a citizen of the United States, residing at Schenectady, county of Schenectady, State ol' New York, have invented certain new and useful improvements in Induction-Motor Control, oi which thc following is a specification.

My invention relates to the control VolV induction-motors used for propelling railwayvehiclcs; and its object is to provide means for maintaining an equal distribution of load on thc several motors at all times.

An oilieient'induction-motor is substantially a synchronous machine-that is, it operates normally with a small slip. Consequently if the driving-wheels of a vehicle are of unequal size, as may frequently be the caso, due to unequal wear, or if two cars or locomotives with wheels of different size are coupled together in a train the synchronous characteristic oi the motors .produces an unequal distribution ol load. Thus, for instance, if the motors operate at full load with a iive per cent. slip and if one driving-wheel is five per cent. smaller than another the motor geared to the larger wheel may he operating at full load with five per cent` slip, while the motor geared to the smaller wheel may he v running at synchronism, and consequently doing no work whatever. if the inequaiity between the wheels is greater than the slipJ the motor geared to the smaller wheel may even he operating as a generator, returning ower to the line, and thereby acting as a lirake to overload further the other motors.

My invention in its vbroadest aspect consiste in providing means for independently adjusting the torque of the several motors, so that the load may be equally distributed at all timos.

More specifically stated, my invention consists in the combination with a luraiity of motors and a switch for control ing the motors simultaneously of inde endcnt adjust-able resistances placed near tlie motors and connected in series with the secondary windings of the several motors, respectively. With this arrangement if the adjustable resistance in serios with the rotor-winding of the motonwhich is connected to the smallest wheel is completely cut out while a certain amount of resistance is left in the seconder y circuit of the motor connected to a larger wheel the ldriving-wheels W and lmotors.

slip oi the latter motor will be increased sc that the torque of both motors may be made the same, although they are running at suinewhat different speeds.

My invention will best hc'understood by reference to the accompanying drawings, in whichp Figure 1 shows diagrammaticallya car or locomotive driven by induction-motors provided with adjusting means arran ed in accordance with my invention, and gig. 2 is a diagram of circuit connections.

In Fig. l, M and Mz represent two induction-motors mechanical] connected to the The Wheel WB is represented as smaller than the Wheel W', and consequently the motor M must run at a higher speed than the motor M. The primaries of the induction-motors are connecte ed, through suitable switches C', to the current-collectors, indicated by the trolleys T. The secondaries of the motors are connected Yin parallel to suitable controllinf-switclies U2, by means of which the secon ary resistences of the motors may be simultaneously varied to control the speed and torque of the vehicle. R and Rz represent adjustable resistances placed near the motors and connected directly in series with their respective secondary windings. By means of these resistances the speed-torque characteristics of the two motors may be adjustable independently, so that they will divide the load equally in spite of the difference in their speeds.

In Fig. 2 I have shown a diagram of the circuit connections. In this figure I have shown the switch C in the primary circuit arranged as a reversing-switch and the switch C arranged to connect variable portions of resistance R in circuit with the secondary' windin s of the motors, which are connected in para lel. It will be understood that the particular arrangement of these controllingswitches C and C2 forms no part of my :present invention, and these switches may be modified in any desired manner to control the motors in any well-known way. The rilnary windings of the motors are indicated vy M and M respectively, and the secondaryi windings hy m and m. It' and R represent independent ad'ustable resistencias connected in the secon ary circuits offtrhe The resistance R', which is in the secondary circuit of the motor M, which is l supposed to be connected to the smaller driving-wheel, is shown entirely cut out of' the circuit, while a portion of the resistance lt is left in circuit with the secondary winding m. With this arrangement the two motors will have equal torques at speeds diilering in amount, depending on the design of the motors and the amount of resistance R in the secondary winding m.

-I'do not desire to limit myself to the particular cohstruction and arrangement of parts here shown, but jaim in the a pended 4claims to cover all modications w 1ch are within the scope of my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, isE

1. In combination with a vehicle, a plurality of induction motors mechanically connected to 'the driving-wheels of said vehicle, means under the control of the motorman f or controlling said motors simultaneously, and means for adjusting the relative turques of said motors.

2. In combination with a vehicle, a plurality of induction motors mechanically connected to the driving-wheels of said vehicle,

means under the control of the motorman for controlling said motors simultaneously, and means for adjusting independently the relative rcsistances of thefsecondary circuits of said motors.

3. 4In combination with a vehicle, a plurality of induction motors mechanically conner-.ted to the drivingwl|ccls of said vehicle, at controlliiig-switcli adapted to vary simultaneously thc resistanccs in thc secondary circuits of said motors to control the speed of the vehicle, and means for adjusting,r independently the relative rcsistances in the secondary circuits of said motors to vary the relative speed-torque characteristics oi said motors.

4. In combination with a vehicle, a )lurality of induction motors mechanically con nected to the driving-wheels oi said vehicle, a switch under the control of the motorman for controlling said motors simultaneously, and independent adjustable resistances placed near the several motors and connected in their secondary circuits.

5. In combination with a vehicle, a lurality of induction Nmotors mechanical y connected to the (having-wheels of said vehicle, the secondary Whdings of the several motors being connected electrically in parallel, a controlling-switch in the secondary circuit ada ted to vary the resistance therein, and ingependent adjustable resistances connected in series with the several rotor-windings respectively.

In witness whereof I have hereunto set my hand this 27 th day of' June, 1905.

ALBERT H. ARMSTRONG.

Witnesses:

BENJAMIN B. HULL7 HELEN ORFORD. 

